1. Field of the Invention
The present invention relates to a printer for printing characters and symbols, etc., on a printing medium while moving a carriage having a printing head thereon in the printing line direction.
2. Description of the Prior Art
Various types of printers are employed in information processing and business machines. One type of such printer frequently employed in recent years includes a printing head having many printing wires extending almost perpendicularly to the direction of a printing line and mounted on a carriage for movement in the direction of the printing line so that character data are printed on a printing medium one line at a time. This type of printer can be miniaturized and made light of weight, and thus is available at a low price. The printer selectively strikes the printing medium with printing wires via an inked ribbon for printing. A carriage of the printer having thereon an inked ribbon casing including the inked ribbon therein as well as a printing head including the printing wires thereon is moved in the direction of the printing line, while the printing medium is fed in a direction substantially perpendicularly to the direction of the printing line.
Although the carriage is moved in the direction of the printing line direction by use of a toothed belt and a screw shaft, another type of carriage, called a self-propelled carriage mechanism and employing a rack and a pinion for moving the carriage, has begun to be profitably employed.
Such a self-propelled carriage mechanism, as disclosed for example in U.S. Pat. No. 4,523,486, comprises in general an inked ribbon feed mechanism mounted on a carriage frame, and a flexible cable connected with this mechanism. A motor for self-propulsion of the mechanism is located on the lower surface of the carriage frame. Pinions are attached to opposite ends of a shaft of the motor, a lower of the pinions being engaged with a rack mounted on a printer frame to propel the mechanism, and an upper of the pinions being engaged with a gear of the inked ribbon feed mechanism for feeding an inked ribbon. Thus, the self-propelled carriage mechanism is arranged such that a movable body is connected with a flexible cable.
Such arrangement includes attaching the inked ribbon feed mechanism to the carriage frame by screws, and inserting a plug at the end of the flexible cable into a socket provided on the carriage frame for electrical connection. Moreover, although a ribbon cable or the like may be employed, hereinafter such is referred to by the term flexible cable.
However, with this known carriage mechanism, the inked ribbon mechanism must be attached to the carriage frame by screws to assemble a printer. For this, alignment of tapped holes with screws is required together with screwing of screws into the tapped holes. That is, in an assembly line process of automatic assembly, such operations as longitudinal and transversal positioning of tapped holes and screws, insertion of the screws into the tapped holes, and rotation for screwing the screws into the holes are needed. These operations are complicated and cause the assembly line to become intricate because of the many operating processes required therefor. Furthermore, the socket and the plug must be aligned with each other for a subsequent insertion operation, and this likewise is complicated.
In addition, such prior carriage mechanism has another disadvantage that repetitive bending of a flexible cable due to reciprocating movement of the carriage causes bending stress to be concentrated in the vicinity of a connection portion between the flexible cable and the plug. As a result, the conductor pattern is sharply deteriorated and can become disconnected near the connecting portion.